<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div>
    你喜欢的颜色：<input type="color" name="favcolor" id="">
    <br>
    <input id="submit" type="submit" value="提交">
  </div>
  <script>
    let btn = document.getElementById('submit');
    btn.onclick = function() {
      let value = document.querySelector('input[type=color]').value;
      alert('你喜欢的颜色是：' + value);
    }
  </script>
</body>
</html>